A Failed Experiment

In my opinion the "footnotes" in the history of Artificial Intelligence were not just footnotes: they represent colossal failures. They were all great ideas. In fact, they were probably the "right" ideas: of course, an intelligent machine must be capable of conversing in natural language; of course, it must be able to walk around, look for food, and protect itself; of course, it must be able to understand what people say (each person having a slightly different voice); of course, it would make more sense for software to "evolve" by itself than to be written by someone (just like any form of intelligent life
did); of course, we would expect an intelligent machine to be able to write
software (and build other machines, like we do); of course, it would be nice if
the machine were capable of translating from one language to another; of
course, it would make sense to build a computer that is a replica of a human
brain if what we expect is a performance identical to the performance of a
human brain.

These ideas have remained unfulfilled. In a sense, Artificial Intelligence is still a failed experiment: we still don't know how to do it properly.

Note that, ironically, it was A.I. that made computers popular and fueled progress in computer science. The idea of a thinking machine, not the usefulness of computers, drove the initial development. Since those days, progress in A.I. has been scant, but computers have become household appliances. Your laptop and smartphone are accidental by-products of a failed scientific experiment.